In a receiver, since the receiver needs to amplify a received weak signal, the gain of the receiver is very high and typically may be up to 60 dB-80 dB. A high-gain circuit usually has a relatively large direct current offset due to an unmatched circuit. This is the case for the receiver. The circuits of the receiver will enter an abnormal working state due to the direct current offset of the receiver, such that circuit properties, even functions such as error vector magnitude (EVM), gain and the like of the receiver, are affected. The DCOC is provided for solving this problem.
There are many implementation methods for the DCOC. Common methods include an input offset storing method, an output offset storing method, a pre-amplification method and a negative feedback loop method, etc. Each of the methods above can implement the cancellation of the offset. However, all of the methods are implementations based on a dynamic calibration. Such methods have the defects of slow calibration and convergence speeds and are not suitable for an application occasion of the receiver.